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Fit a curve y=ax+bx2 for the data; | x : | 1 | 2 | 3 | 4 | 5 | 6 || y : | 2.51 | 5.82 | 9.93 | 14.84 | 20.55 | 27.06 |
1 Answer
| written 4.6 years ago by |
| x | 1 | 2 | 3 | 4 | 5 | 6 | 21 |
|---|---|---|---|---|---|---|---|
| y | 2.51 | 5.82 | 9.93 | 14.48 | 20.55 | 27.06 | 80.35 |
| x2 | 1 | 4 | 9 | 16 | 25 | 36 | 91 |
| xy | 2.51 | 11.64 | 29.79 | 57.92 | 102.75 | 162.36 | 366.97 |
| x3 | 1 | 8 | 27 | 64 | 125 | 216 | 441 |
$y=ax+bx^2 \\ \sum y =a \sum x + b \sum x^2 \\ 80.35 = 21a+91b \ \cdots (A)$
Also,
$xy=ax^2+bx^3$
$\sum xy = a \sum x^2 + b \sum x^3$
$366.97=91a+441b \ \cdots (B)$
Solving (A) and (B) simultaneously,
$a\approx 2, \ b\approx 0.4$
Hence, the required curve for the given data is
$y=2x+0.4x^2$